Background tank fill based on refrigerant composition

ABSTRACT

A portable recovery unit for automatically filling a background tank of blended refrigerant includes a main tank for holding recovered refrigerant from a vehicle A/C system which has a first chemical composition, and an auxiliary tank for holding an auxiliary supply of fresh refrigerant which has a second refrigerant composition. The auxiliary tank is arranged in fluid communication with the main tank so that fluid can be transferred from the auxiliary tank to the main tank. An electronic controller controls the flow of fluid from the auxiliary tank to the main tank. A refrigerant identifier is coupled to the main tank to sample and analyze the refrigerant in the main tank in order to determine the chemical composition of the refrigerant in the main tank, so the refrigerant in the main tank can be purified to an acceptable level based on that analysis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of pendingU.S. patent application entitled, Background Tank Fill Based OnRefrigerant Composition, filed Dec. 7, 2007, having a Ser. No.11/952,489, the disclosure of which is hereby incorporated by referencein its entirety.

FIELD OF THE INVENTION

The disclosure relates generally to automotive vehicle air conditioningsystems, and more specifically to refrigerant recovery units forrecovering and recycling blended refrigerant from an automotive vehicleair conditioning (hereinafter “A/C”) system.

BACKGROUND OF THE INVENTION

Automotive vehicle A/C systems require maintenance. Maintenance includesrefrigerant recovery, evacuation and recharging of the A/C system.Portable refrigerant recovery units are used in connection with thismaintenance. The refrigerant recovery units connect to the A/C system ofthe automotive vehicle to recover refrigerant out of the system,separate out contaminants and oil, and recharge the system withadditional refrigerant.

SUMMARY OF THE INVENTION

At least one embodiment of the disclosure is a unit for recoveringrefrigerant from a vehicle A/C system, which includes a first containerfor holding a primary supply of refrigerant having a first refrigerantcomposition, and a second container for holding a secondary supply ofrefrigerant having a second refrigerant composition. The secondcontainer is in fluid communication with the first container so fluidcan be transferred from the second container to the first container. Anelectronic controller means is provided for controlling the transfer offluid from the second container to the first container. A compositionanalyzing device is operatively engaged to the first container andconstructed and arranged to determine the chemical composition of therefrigerant in the first container.

Other embodiments provide, a method for using a refrigerant recoveryunit for adjusting a chemical composition of refrigerant recovered froma refrigerant system comprises weighing the recovered refrigerant toobtain a weight; comparing the weight of the recovered refrigerant to aminimum weight; analyzing the chemical composition of the recoveredrefrigerant; and comparing the chemical composition of the refrigerantto a target composition.

Still other embodiments show a method for using a refrigerant recoveryunit to adjust the composition of a recovered refrigerant comprisesweighing the recovered refrigerant; comparing the weight of therecovered refrigerant to a minimum weight; adding a rechargingrefrigerant to the recovered refrigerant to form a combined refrigerant,the recharging refrigerant having a predetermined chemical compositionof chemical components by percentage of weight of each component;weighing the combined refrigerant; and comparing the weight of thecombined refrigerant with a maximum weight.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are, of course, additional embodimentsof the invention that will be described below and which will form thesubject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary front plan view of an example refrigerantrecovery unit shown with a portion of the front cover removed toillustrate major components of the unit.

FIG. 2 is a fragmentary rear plan view of the refrigerant recovery unitshown in FIG. 1.

FIG. 3 is a flow diagram of the refrigerant recovery unit shown in FIGS.1 and 2.

FIG. 4 is a schematic diagram of a portion of the diagram shown in FIG.3 relating to the automatic filling aspect of the main tank based onrefrigerant composition.

FIG. 5 is a flow chart illustrating an example of operations that may beperformed by a refrigerant recovery cart for transferring refrigerantfrom the auxiliary tank to the main tank based on refrigerantcomposition.

DETAILED DESCRIPTION

The invention will now be described with reference to the drawingfigures, in which like numerals refer to like parts throughout. FIGS.1-2 show a portable recovery unit 10 for recovering and recyclingrefrigerant from a refrigerant system, such as in an automotive vehicle.The unit 10 includes a first container or main tank 12 for holding aprimary supply of refrigerant. The main tank 12 may also be referred toas an internal storage vessel (ISV). The primary supply of refrigerantor recovered refrigerant contains refrigerant that has been recoveredfrom the A/C system. The unit 10 also includes a second container orauxiliary tank 14 for holding a secondary supply of refrigerant. Thesecondary supply of refrigerant has a known chemical composition, and issometimes referred to as fresh refrigerant, virgin refrigerant orrecharging refrigerant. The auxiliary tank 14 is arranged in fluidcommunication with the main tank 12 so fluid can be transferred from theauxiliary tank 14 to the main tank 12. An electronic controller means inthe form of an electronic controller 16 for controlling the transfer offluid from the auxiliary tank 14 to the main tank 12 based onrefrigerant composition is provided. A composition analyzing device 18is operatively engaged with the main tank 12 and constructed andarranged to determine the chemical composition of the refrigerant in themain tank 12.

Details of the structure and operation of the example embodiment ofrefrigerant recovery unit 10 is illustrated in several of the figures.FIG. 1 shows one example of a refrigerant recovery unit 10 for servicinga refrigerant system of a vehicle A/C system. The refrigerant recoveryunit 10 is a machine mounted within a cabinet 20 supported by a pair ofwheels 22, such that it is portable. The refrigerant recovery unit 10may include a high pressure hose 24, typically color coded red, with acoupling 26 for coupling to the vehicle's high pressure port and a lowpressure hose 28, typically color coded blue, having a coupling 30 forcoupling to the low pressure port of the vehicle's refrigerant circuit.In some refrigerant systems, there may be only one port, for example,where the recovery or low pressure port is eliminated. In such systems,the refrigerant recovery unit may be configured with one hose, inaccordance with the principles of the invention. The front panel of thecabinet 20 is shown broken away in FIG. 1 to show the major elements ofthe refrigerant recovery unit 10.

The refrigerant recovery unit 10 includes the electronic controller 16including a microprocessor on a circuit board 17 for controlling anelectromechanical solenoid valve 134, shown in the flow diagram of FIG.4. Optionally, the controller may include a memory unit to storesoftware and data, and the microprocessor may be coupled to the memoryunit for executing the software stored in the memory unit. Theelectronic controller receives data signals from the pressure sensorsand control switches on the control panel 32, shown in FIG. 1, as wellas from the composition analyzing device 18, and a weighing device 34.The composition analyzing device may be an infrared analyzing device,for example, which analyzes the refrigerant composition with gaschromatography, although this is not the only way the refrigerant can besampled. The weighing device is the example embodiment is a load cell,but the weighing device can be an electronic scale or any other type ofweighing device configurable to transmit a weight data signal to thecontroller 16. The control panel 32 includes an on/off switch 35 and adisplay 36 for displaying the operational status of the machine'soperation. The display may be an LCD display or other suitableelectronic display that is coupled to the controller 16 by way of aconventional input/output circuit. The display panel 30 further includesa switch panel 38 having a conventional keyboard 40, and a plurality ofpushbutton switches 42 for controlling the operation of the unit 10through its various phases of operation and/or for selecting parametersfor display. The keyboard 40 in conjunction with operational switches 42and display 36 allow the operator to enter the desired operationalparameters for the unit 10 according to manufacturer specifications forthe servicing of an A/C system in a particular vehicle.

The input hoses 24 and 28 are coupled to mechanical pressure gauges 44and 46, respectively, which are mounted on the front panel ofrefrigerant recovery unit 10, as seen in FIG. 1. In addition, electricalpressure transducers 44′ and 46′ are coupled to the hoses 24 and 28, andare coupled to the controller 16 through conventional input/outputcircuits to provide the controller 16 with pressure information duringoperation of the unit 10. Gauges 44 and 46 provide the operator with aconventional analog display of the pressure as well. Mounted to the topsurface 48 of cabinet 20 is a sight gauge 50 which also includes anintegral replaceable filter cartridge 52 mounted to the cabinet 20 forfiltering particulate material from the refrigerant during the flushingcycle.

Mounted to the floor 54 of cabinet 20 is a compressor 56 and a vacuumpump 58. Behind the front of cabinet 20 on floor 54, is mounted the maintank 12 of refrigerant (FIG. 2) for the supply of refrigerant to thesystem being serviced. Also mounted adjacent the main tank 12 is theauxiliary supply tank 14 which supplies additional refrigerant to themain tank 12, as described in greater detail below. Mounted to theinside of rear wall 60 of cabinet 20 is an oil accumulator tank 62, acompressor oil separator filter 64, a manifold 66 (shown as a node inFIG. 3), and a condenser 68. In addition, a fresh oil canister 70 ismounted within a side compartment of cabinet 20. A recovery oilcontainer 72 is mounted on the lower part of the cabinet 20 to receiveoil drained from the accumulator tank 62.

As shown in FIG. 2, the main tank 12 rests on the weighing device 34,which in this example is load cell. The weighing device 34 provides aweight data signal to the controller 16 such that the weight of the tankcomprising its tare weight plus the weight of refrigerant therein ismonitored by the controller 16. In addition, the composition analyzingdevice 18 is coupled to the main tank 12 and coupled to the controller16 to provide a signal to the controller 16 indicating the chemicalcomposition of the refrigerant in the main tank 12. Mounted adjacent themain tank 12 is an auxiliary tank 14 which is plumbed to the main tank12, as shown in FIG. 3. High pressure hoses and connectors together withcontrol valves couple tank 14 to tank 12. Refrigerant recovery unit 10also includes a handle 74 to facilitate portability of the refrigerantrecovery unit 10.

Having briefly described the major components of the refrigerantrecovery unit 10 shown in FIGS. 1 and 2, a more detailed description ofthe system follows in connection with FIG. 3, followed by the specificoperation of the system of the refrigerant additional system asdescribed in connection with FIGS. 4 and 5.

Initially, the hoses 24 and 28 are coupled to the vehicle and therecovery cycle is initiated by the opening of the dual back-to-back highpressure and low pressure solenoids 76, 78, respectively (FIG. 3). Thisallows the refrigerant within the vehicle to flow through conduits 80through check valve 82 and recovery valve 84 into the manifold 66. Therefrigerant then flows through valve 88 and unit 90 via conduit 92 intothe accumulator tank 62 where it travels through an output conduit 94through a water separating molecular sieve 96 to the input of compressor56. Refrigerant is drawn through the compressor 56 through a valve 98and through the oil separating filter 100, which circulates oil back tothe compressor 56, through conduit 102 through oil return valve 104. Therefrigerant recovery unit 10 may optionally include a high pressureswitch 106. Transducer 106 is coupled to the microprocessor which isprogrammed to determine the upper pressure limit of, for example, 435psi to shut down the compressor 56 in the event the pressure becomesexcessive. The compressed refrigerant then exits the oil separator 100through conduit 108, travels through check valve 110 and then through aheating coil 112 in accumulator tank 62 via conduit 114. The refrigerantrecovery unit 10 optionally includes a low pressure switch 86 thatsenses the pressure and provides an output signal coupled to themicroprocessor through a suitable interface circuit programmed to detectwhen the pressure has recovered refrigerant down to 13 inches ofmercury. The heated compressed refrigerant flowing through heating coil112 assists in maintaining the temperature in accumulator tank 62 withina working range. The refrigerant then flows through conduit 116 to thecondenser 68 which cools the compressed refrigerant which next flowsthrough check valve 144 and into the main tank 12.

The evacuation cycle begins by the opening of solenoids 76 and 78 andvalve 130, leading to the input of vacuum pump 58. Prior to openingvalve 130, air intake valve 132 is opened, allowing the vacuum pump 58to start up exhausting air through outlet 59. The vehicle system 124,which is at a relatively low pressure at the end of the flush cycle isthen evacuated by the closing of valve 132 and the opening of valve 130,allowing the vacuum pump 58 to exhaust any trace gases remaining untilthe pressure is approximately 29 inches of mercury. When this occurs, asdetected by pressure transducers 44′ and 46′ coupled to the controller16, the controller 16 actuates valve 130 by turning it off and therecharging cycle begins.

The recharging cycle begins by opening charge valve 122 and solenoids 76to allow the liquid refrigerant in tank 12, which is at a pressure ofapproximately 70 psi or above, to flow through conduit 80. The flow isin the direction indicated by arrow A through high-pressure solenoids 76for a period of time programmed to provide a full charge of refrigerantto the vehicle.

The automatic tank fill structure for filling a tank in the backgroundis now described in connection with FIGS. 3-4 followed by a descriptionof its operation in accordance with the flow chart of FIG. 5. The maintank 12 includes recovered refrigerant. The auxiliary supply tank 14includes fresh or virgin refrigerant, and is the same type used in themain tank 12. The auxiliary tank 14 is coupled by way of a plumbingconnection to the solenoid actuated valve 134 by means of a highpressure conduit 136. A conduit 138 couples the solenoid actuated valve,which is coupled to the microprocessor, to the manifold 66.

The filling path is through the pathway indicated by arrow C, shown inFIG. 3. The controller 16 applies a signal to open the solenoid actuatedvalve 134, as described in connection with FIG. 4 below When thesolenoid actuated valve 134 is opened, refrigerant from the auxiliarytank 14 flows into tank the main tank 12, through conduit 136, valve134, conduit 138, then through the manifold 66. This path includes theaccumulator tank 62, to which a low pressure or vacuum switch 86 isoptionally coupled, filter 96, compressor 56, separator 100, backthrough the cooling coil 112 of accumulator tank 62, through check valve110, through condenser 68 and check valve 144 into the main tank 12. Thelow pressure sensor switch 86 also sends a signal to the microprocessorproviding an alarm signal to the operator indicating when the auxiliarysupply tank 14 is emptied and being pulled into a vacuum. When thisoccurs, sufficient refrigeration exists in main tank 12 to allowcompletion of a recharging cycle of the refrigerant circuit, and alsoallow the operator to reconnect a fresh auxiliary tank 14, as required.For such a purpose, it is understood that tank 14, which can be of aconventional design, includes a shut-off valve for coupling conduit 136thereto.

This transfer process is controlled by the controller 16 which actuatesthe solenoid actuated valve 134 to fill the main tank 12 based on thecomposition data signal received from the composition analyzing device18, coupled to the main tank 12. This is not the only way to fill themain tank 12, the controller could operate to fill the main tank 12based on weight data received from the load cell. The compositionanalyzing device 18 or refrigerant identifier is coupled to the maintank and operatively engaged to the controller 16 to provide acomposition data signal to the controller 16. The composition analyzingdevice 18 is continuously monitoring the refrigerant composition,although continuous monitoring is not required. The compositionanalyzing device 18 could sample the refrigerant composition at discretetime intervals. The main tank 12 is arranged on a weighing device, suchas a scale or load cell. The weighing device provides a weight datasignal to the controller 16.

The operation of the system to incrementally add refrigerant from theauxiliary tank 14 to main tank 12, in addition to initially filling themain tank 12, is now described in connection with FIG. 5. Such operationassures that the main tank 12 will always have an adequate supply ofrefrigerant for the next service of a refrigeration circuit.

The programming of the microprocessor begins with the normal operationof the refrigerant recovery unit 10 through a recovering/rechargingmode, as indicated by block 200. The program then determines if the unit10 has been in operation for five minutes or more, as indicated by block202. Although the period of idling is selected to be five minutes inthis example, a shorter or longer period of time may also be selected inaccordance with principles of the invention. If the unit 10 has not beenidling for the requisite period of time, for example, when there is anextended period of time between one vehicle service and the next and therefrigerant recovery unit 10 has been shut-off, the unit 10 returns tothe normal unit operation 200. If the refrigerant recovery unit 10 hasbeen idle for five minutes, the program determines, as indicated byblock 204, the weight of the refrigerant in the main tank 12, asdetermined by a signal from the load cell 34. After recharging a vehiclerefrigerant system, it may be that the refrigerant recovery unit 10 islow on refrigerant in the main tank 12. In such a case, there may be aninsufficient amount of refrigerant in the main tank 12 to complete thenext servicing. If the supply remains above a predetermined minimumweight, in this example five pounds, the refrigerant recovery unit 10determines if the refrigerant in the main tank 12 has an acceptablelevel of purity, as indicated by block 206. This is important forblended refrigerants. Blended refrigerant has multiple chemicalcomponents that will separate when they leak from an A/C system or arerecovered; that is, one component tends to bleed off more than anotherdue to the different densities of the components. If the purity level isacceptable, meaning it falls within a target range of a refrigerantcomposition, then the refrigerant recovery unit 10 returns to normalunit operation 208. The target composition may be in terms of percentageby weight composition of an ideal composition of the blendedrefrigerant. If the supply of refrigerant in the main tank 12 is belowfive pounds, then a transfer of refrigerant is initiated from theauxiliary tank 14 to the main tank 12, as indicated by block 210. Thetransfer is initiated by actuating the solenoid actuated valve 134,which is controlled by the controller 16. Optionally, the programcontinues testing to determine whether the low pressure sensor 86indicates that tank 14 is in a vacuum or below atmospheric pressure asindicated by block 212. If it is, the controller 16 sends a signal todisplay 32 to prompt the operator to replace the refrigerant supply tank14, as indicated by block 214. However, it is to be understood thatblocks 212 and 214 are not required, and that these steps can also bemodified. If the low pressure sensor 86, however, does not detect avacuum condition in the manifold 66 coupled to the auxiliary tank 14when valve 92 is operated, the program then determines, as indicated byblock 216, to determine whether the supply of refrigerant in the maintank 12 is above a predetermined maximum weight, in this example twentypounds. Twenty pounds, in this example, represents a full or nearly fulltank of refrigerant. If the supply of refrigerant in the main tank 12 isabove twenty pounds, the program returns to normal unit operation 208.If this condition is not met, the program again samples the purity levelof the refrigerant in the main tank 12 with composition analyzing device18, as indicated by block 218. If the purity level is acceptable, theunit 10 then returns to normal unit operation 208. However, if thepurity level is not acceptable, the system returns to block 210 toinitiate a transfer of additional refrigerant from the auxiliary tank 14to the main tank 12, effectively diluting the refrigerant in the maintank 12 to achieve the desired purity level. However, there may be someinstances in which the change in composition of the refrigerant is toosevere for recycling with the refrigeration recovery unit 10, in whichcase, the refrigerant in the main tank 12 would have to be returned tothe manufacturer or other party for purification. Thus, the solenoidactuated valve 134 will be actuated during the normal operation throughthe flow path indicated by arrow C to draw additional refrigerant asrequired to the main tank 12.

Thus, with the system of the present invention, a supply of refrigerantwith an acceptable purity level remains available during all operatingconditions, which assures uninterrupted servicing of a refrigerantsystem of a vehicle or other system being serviced.

The many features and advantages of the invention are apparent from thedetailed specification, and thus, it is intended by the appended claimsto cover all such features and advantages of the invention which fallwithin the true spirit and scope of the invention. Further, sincenumerous modifications and variations will readily occur to thoseskilled in the art, it is not desired to limit the invention to theexact construction and operation illustrated and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the invention.

What is claimed is:
 1. A refrigerant recovery system, comprising: acomposition analyzing device configured to analyze a chemicalcomposition of a first refrigerant; a controller, of the refrigerantrecovery system, operatively connected to the composition analyzingdevice to receive a signal from the composition analyzing device tocommunicate to the controller the chemical composition of the firstrefrigerant; and a valve and conduit system, of the refrigerant recoverysystem, configured to selectively place the first refrigerant in fluidcommunication with a second refrigerant, wherein the valve and conduitsystem is operatively connected to the controller to allow thecontroller to operate the valve and conduit system to allow a certainamount of the first and second refrigerants to mix together.
 2. Therefrigerant recovery system of claim 1, wherein the controller isconfigured to allow the first and second refrigerants to achieve atarget chemical composition.
 3. The refrigerant recovery system of claim1, further comprising a first and second tank configured to contain oneof the first and second refrigerants.
 4. The refrigerant recovery systemof claim 3, wherein the first and second refrigerants mix together, inone of the first and second tanks.
 5. The refrigerant recovery system ofclaim 3, further comprising a weighing device configured to weigh one ofthe first and second tanks.
 6. The refrigerant recovery system of claim1, further comprising an oil separator configured to separate oil fromone of the first and second refrigerants.
 7. The refrigerant recoverysystem of claim 1, wherein the composition analyzing device is arefrigerant identifier.
 8. The refrigerant recovery system of claim 1,wherein the composition analyzing device is an infrared analyzingdevice.
 9. The refrigerant recovery system of claim 1, wherein the valveand conduit system includes a solenoid actuated valve.
 10. Therefrigerant recovery system of claim 9, wherein the solenoid actuatedvalve is operatively connected to the controller.
 11. The refrigerantrecovery system of claim 1, wherein the valve and conduit systemincludes a check valve.
 12. A refrigerant recovery system, comprising:means for analyzing a composition configured to analyze a chemicalcomposition of a first refrigerant; means for controlling, of therefrigerant recovery system, operatively connected to the means foranalyzing to receive a signal from the means for analyzing tocommunicate to the means for controlling the chemical composition of thefirst refrigerant; and means for valving configured to selectively placethe first refrigerant in fluid communication with a second refrigerant,wherein the means for valving is operatively connected to the means forcontrolling to allow the means for controlling to operate the means forvalving to allow a certain amount of the first and second refrigerantsto mix together.
 13. The refrigerant recovery system of claim 12,wherein the means for controlling is configured to allow the first andsecond refrigerants to achieve a target chemical composition.
 14. Therefrigerant recovery system of claim 12, further comprising a first andsecond tank configured to contain one of the first and secondrefrigerants.
 15. The refrigerant recovery system of claim 14, whereinthe first and second refrigerants mix together, in one of the first andsecond tanks.
 16. A refrigerant recovery unit, comprising: a compositionanalyzing device configured to analyze a chemical composition of a firstrefrigerant contained in a refrigerant container; a controller, of therefrigerant recovery unit, operatively connected to the compositionanalyzing device to receive a signal about the chemical composition ofthe first refrigerant from the composition analyzing device; a scale, ofthe refrigerant recovery unit, configured to weigh the refrigerantcontainer, wherein the scale communicates with the controller, whichdetermines based on a measured weight of the refrigerant container whento add a second refrigerant; and a valve and conduit system, of therefrigerant recovery unit, configured to selectively place the firstrefrigerant in fluid communication with the second refrigerant, whereinthe valve and conduit system is operatively connected to the controllerthat allows a certain amount of the first and second refrigerants to mixtogether in the refrigerant container.
 17. The refrigerant recovery unitof claim 16, wherein the refrigerant container is located within therefrigerant recovery unit.
 18. The refrigerant recovery unit of claim16, wherein the controller adds the second refrigerant when the chemicalcomposition of the first refrigerant is below a predetermined puritylevel.
 19. The refrigerant recovery unit of claim 16, wherein the secondrefrigerant is added incrementally to the refrigerant container.
 20. Therefrigerant recovery unit of claim 16, wherein the second refrigerant isstored in an auxiliary tank.